Field of the Invention
The present invention relates to a radiation imaging apparatus and a radiation imaging system.
Description of the Related Art
Radiation imaging apparatuses that irradiate a target object with a radiation and detect the intensity distribution of the radiation having passed through the target object to obtain the radiation image of the target object are widely used in general for industrial non-destructive inspection and medical diagnosis. Recently, an imaging apparatus has been developed which captures a radiation digital image by using a radiation detection panel configured to convert, into electric information by a sensor, light emitted in correspondence with a radiation entering a scintillator. Such an imaging apparatus can provide an output image instantaneously.
Since such an imaging apparatus can image a wide range of portions quickly, a low-profile, lightweight portable imaging apparatus called an electronic cassette has been developed. Especially in recent years, a wireless imaging apparatus requiring no cable connection has been developed to improve portability. An imaging apparatus of this type is configured to be able to contain or attach a rechargeable battery serving as a power source for supplying power, and has higher portability than a conventional imaging apparatus.
At the time of imaging, the imaging apparatus might receive an impact force or another external force. A glass substrate constituting a radiation detection panel may be broken by the external force. If the glass substrate is broken, it becomes very difficult to capture a radiation image clearly. It is thus advisable to protect the imaging apparatus satisfactorily so as to prevent the breakage of the glass substrate. To operation the internal radiation detection function of the imaging apparatus even in such a situation, the imaging apparatus needs to consider strength, vibration resistance, and shock resistance. At the same time, downsizing, thinning, and weight-saving are requested of the imaging apparatus in order to facilitate handling, improve portability, and enable quick imaging.
For this purpose, imaging apparatuses take various configurations. An imaging apparatus disclosed in Japanese Patent No. 3848288 aims at high rigidity and weight-saving by supporting a radiation detection panel using a base having concave portions, and including the concave portions on the inner surface of the bottom of a housing via a reinforcing plate and a support. An imaging apparatus disclosed in Japanese Patent Laid-Open No. 2010-281753 aims at high rigidity and weight-saving by supporting a radiation detection panel on the inner surface of the bottom of a housing using a base and a structure thereon.
An imaging apparatus disclosed in Japanese Patent Laid-Open No. 2012-181238 aims to increase the strength of the imaging apparatus by constituting a housing with a monocoque structure of a fiber-reinforced resin or the like. In the imaging apparatus disclosed in Japanese Patent Laid-Open No. 2012-181238, a radiation detection panel is held by buffer members attached to two lid members that constitute the side walls of the housing. Japanese Patent Laid-Open No. 2012-181238 discloses a structure in which the radiation detection panel is held by an adhesive layer to the inner wall of the top of the housing. In this manner, downsizing, thinning, and weight-saving of the imaging apparatus have conventionally been performed by various structures.
However, the above-described related arts have several problems. The imaging apparatuses disclosed in Japanese Patent No. 3848288 and Japanese Patent Laid-Open No. 2010-281753 require a base and a support that support a radiation detection panel, in addition to a housing that contains the radiation detection panel. Although the imaging apparatus disclosed in Japanese Patent Laid-Open No. 2012-181238 has a structure in which the housing serving as an exterior ensures rigidity, it additionally requires a supporting member that supports the radiation detection panel within the housing. The supporting member of the radiation detection panel can be a relatively rigid member. However, if the supporting member is satisfactorily rigid, weight-saving becomes difficult. To solve this, rigidity is improved by fastening the supporting member and the housing by a screw or the like, or bringing them into contact. In such a case, however, it tends to be difficult to arrange a control board, rechargeable battery, and the like that need to be stored in the imaging apparatus.
For example, in Japanese Patent Laid-Open No. 2010-281753, a control board that controls the radiation detection panel is arranged outside the radiation detection panel when viewed from the radiation incident direction. In this case, it is hard to employ a so-called slim bezel structure that decreases the distance between the housing and glass substrate of the imaging apparatus that protect the radiation detection panel. Therefore, downsizing of the imaging apparatus becomes difficult.
Japanese Patent Laid-Open No. 2012-181238 introduces an arrangement in which a supporting member that supports the radiation detection panel in the housing is omitted by adhering the radiation detection panel to the inner wall of the top of the housing on the radiation incident surface side. In this arrangement, necessary rigidity needs to be ensured at the top of the housing. A radiation emitted by the radiation source passes through a subject and the top of the housing and then is detected by the radiation detection panel. The top of the housing often has a simple plate-like shape with a uniform plate thickness so that the top does not remain as an artifact in a captured image. It is therefore difficult to improve rigidity by changing the shape of the member, for example, giving a ribbed structure to the top of the housing in order to ensure necessary rigidity. To ensure necessary rigidity, the plate thickness is simply increased, and downsizing and weight-saving of the overall imaging apparatus become difficult. When the radiation detection panel is adhered to the inner surface of the top of the housing, if a load such as an external force is applied to the housing, the external force is readily transmitted to the radiation detection panel, increasing the load. Further, upon application of the external force, a high tensile stress is readily applied to the radiation detection panel owing to a bending stress. This tensile stress readily becomes a cause of breaking the glass substrate constituting the sensor substrate of the radiation detection panel.